The aim of this study was to assess the bio-distribution and metabolic behavior of radio-iodinated IBZM in rats. Routine and improved technologies were used. The results showed that the radio-iodinated IBZM had favorable bio-distribution and metabolic behavior. The radio-distribution was high and the radio-iodinated IBZM remained long in striatum where no metabolic by-products manifested at 30 minutes after injection. These suggested that radio-iodinated IBZM is an excellent dopamine D2 receptor imaging agent for SPECT in humans, and it is stressed that thyroid must be blocked by iodine during the study of imaging.